Well, since the idiot appears to have ignored at least part of the law, I would think one of the lawyers in congress could file an injunction or something of the sort.
That would require will and conviction, something lacking in the GOP. They should simply refuse to do anything until these appointments are voided.
Also, I understand the NLRB needs to have at least one minority party member to function. The GOP member who contemplated resigning when Boeing was being harrassed should do so now.